Antibiotic resistance in bacteria may be an inherent trait or may be acquired by mutation. Bacteria that are resistant to antibiotics become a serious public health threat.
For example, approximately 1% of the population in the world has methicillin-resistant staphylococcus aureus (MRSA), a bacterial strain that is resistant to commonly used antibiotics. Most MRSA infections occur in hospitals and healthcare facilities, such as nursing homes and dialysis centers. It is known as heath-associated MRSA (HA-MRSA). Elderly people or people with weakened immune systems are at a high risk of HA-MRSA infection. Recently, among otherwise healthy people in a wider community, another type of MRSA, community-associated MRSA (CA-MRSA), has been found. CA-MRSA is responsible for serious skin and soft tissue infections and for a serious form of pneumonia.
Infection caused by antibiotic-resistant bacteria is often incurable by existing antibiotics. Thus, there is a need to develop new antibiotic drugs.